If you ever shoot factory ammo, you should consider getting Ammo & Ballistics 5. This resource book lists over 2,600 different loads for 190 cartridge types from 17 Mach 2 up to .700 Nitro Express, including the most popular centerfire and rimfire cartridges (both rifle and handgun). There are over 1,400 tables with ballistics data for nearly all commercially-loaded hunting ammunition sold in the United States (as of 2013, the publication date). Tables include velocity, energy, wind drift, bullet drop, and ballistic coefficient.
This book can be helpful when choosing ammo for a hunt. You can quickly compare the velocity and knock-down power of various types of commercial ammo. In addition, this book can help you choose a caliber/chambering for your next hunting rig, as you can compare factory load options.
Book Purchaser Reviews
“The data contained in this book is invaluable. If you don’t understand momentum vs. energy, MER and MEPBR, this book will help you gain an understanding. If you don’t know what the Taylor Knock Out (KO) Index is, this book will enlighten and inform.” — Daryl ID
“Great heaps of data! This volume has pages and pages of new data for .22LR like the hot Velocitor, and also on the .22 WMR from 30 grains up into the 50s. Most importantly there is lots of range data, drop, windage, kinetic energy, etc. — Terrific reference guide….” — E. Svanoe
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In this .308 Win test, 70° F ammo shot 96 FPS slower than ammo heated to 130.5° F. And the 130.5° ammo was 145 fps faster than ammo right out of the freezer (at 25.5° F). That’s a huge difference…
EDITOR’s NOTE: The Sierra tester does not reveal the brand of powder tested here. Some powders are much more temp sensitive than others. Accordingly, you cannot extrapolate test results from one propellant to another. Nonetheless, it is interesting to see the actual recorded velocity shift with ammo temperature variations in a .308 Win.
Written by Sierra Chief Ballistician Tommy Todd This story originally appeared in theSierra Bullets Blog
A few weeks ago I was attending the Missouri State F-Class Match. This was a two-day event during the summer and temperatures were hot one day and hotter the next. I shot next to a gentleman who was relatively new to the sport. He was shooting a basically factory rifle and was enjoying himself with the exception that his scores were not as good as he hoped they would be and he was experiencing pressure issues with his ammunition. I noticed that he was having to force the bolt open on a couple of rounds. During a break, I visited with him and offered a couple of suggestions which helped his situation somewhat and he was able to finish the match without major issues.
He was shooting factory ammunition, which is normally loaded to upper levels of allowable pressures. While this ammunition showed no problems during “normal” testing, it was definitely showing issues during a 20-round string of fire in the temperatures we were competing in. My first suggestion was that he keep his ammunition out of the direct sun and shade it as much as possible. My second suggestion was to not close the bolt on a cartridge until he was ready to fire. He had his ammo in the direct sunlight and was chambering a round while waiting on the target to be pulled and scored which can take from a few seconds to almost a minute sometimes.
This time frame allowed the bullet and powder to absorb chamber [heat] and build pressure/velocity above normal conditions. Making my recommended changes lowered the pressures enough for the rifle and cartridge to function normally.
Testing Effects of Ammunition Temperature on Velocity and POI
After thinking about this situation, I decided to perform a test in the Sierra Bullets underground range to see what temperature changes will do to a rifle/cartridge combination. I acquired thirty consecutive .30 caliber 175 grain MatchKing bullets #2275 right off one of our bullet assembly presses and loaded them into .308 Winchester ammunition. I utilized an unnamed powder manufacturer’s product that is appropriate for the .308 Winchester cartridge. This load is not at the maximum for this cartridge, but it gives consistent velocities and accuracy for testing.
I took ten of the cartridges and placed them in a freezer to condition.
I set ten of them on my loading bench, and since it was cool and cloudy the day I performed this test I utilized a floodlight and stand to simulate ammunition being heated in the sun.
I kept track of the temperatures of the three ammunition samples with a non-contact laser thermometer.
The rifle was fired at room temperature (70 degrees) with all three sets of ammunition. I fired this test at 200 yards out of a return-to-battery machine rest. The aiming point was a leveled line drawn on a sheet of paper. I fired one group with the scope aimed at the line and then moved the aiming point across the paper from left to right for the subsequent groups.
NOTE that the velocity increased as the temperature of the ammunition did.
The ammunition from the freezer shot at 2451 fps.
The room temperature ammunition shot at 2500 fps.
The heated ammunition shot at 2596 fps.
The tune window of the particular rifle is fairly wide as is shown by the accuracy of the three pressure/velocity levels and good accuracy was achieved across the board. However, notice the point of impact shift with the third group? There is enough shift at 200 yards to cause a miss if you were shooting a target or animal at longer ranges. While the pressure and velocities changed this load was far enough from maximum that perceived over pressure issues such as flattened primer, ejector marks on the case head, or sticky extraction did not appear. If you load to maximum and then subject your ammunition to this test your results will probably be magnified in comparison.
This test showed that pressures, velocities, and point-of-impact can be affected by temperatures of your ammunition at the time of firing. It’s really not a bad idea to test in the conditions that you plan on utilizing the ammo/firearm in if at all possible. It wouldn’t be a bad idea to also test to see what condition changes do to your particular gun and ammunition combination so that you can make allowances as needed. Any personal testing along these lines should be done with caution as some powder and cartridge combination could become unsafe with relatively small changes in conditions.
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Long Range Success with Lapua Scenars
With the interest in ultra-long-range shooting in the USA, we thought you might like to see how they shoot out past 2000 meters in Scandinavia. Recently, a new Norwegian long range record was shot in Sokndal in Norway, at the Bøstøl shooting range, using Lapua 300 grain Scenar bullets.
With the target at 2165 meters (1.345 miles), the shooters managed 2/10 hits on steel. The cartridge (as you might expect) was the powerful .338 Lapua Magnum. The load was 89 grains of Vihtavuori N570 pushing the 300gr Scenars at 815 ms (2674 fps). The firearm used was Accuracy International .338 LM AXMC rifle with 27″ barrel and suppressor. Before the record hits at 2165 meters, the team also engaged targets at 1639m, 1710m, and 1850m scoring 4/10 hits on 95 x 100 cm steel target (that’s roughly one meter square, just over 3 feet per side).
About the Location — Sokndal, Norway
Sokndal is the southernmost municipality in Rogaland county, Norway. It is located in the traditional district of Dalane. The administrative center of the municipality is the village of Hauge. Other villages in Sokndal include Li, Rekefjord, Sogndalsstranda, and Åna-Sira.
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Photo 1: Three Near-Equal-Weight 7mm Bullets with Different Shapes
TECH TIP: Bullets of the same weight (and caliber) can generate very different pressure levels due to variances in Bearing Surface Length (BSL).
Bullet 1 (L-R), the RN/FB, has a very slight taper and only reaches its full diameter (0.284″) very near the cannelure. This taper is often seen on similar bullets — it helps reduce pressures with good accuracy. The calculated BSL of Bullet 1 was ~0.324″. The BSL of Bullet 2, in the center, was ~0.430”, and Bullet 3’s was ~ 0.463″. Obviously, bullets can be visually deceiving as to BSL!
This article from the USAMU covers an important safety issue — why you should never assume that a “book” load for a particular bullet will be safe with an equal-weight bullet of different shape/design. The shape and bearing surface of the bullet will affect the pressure generated inside the barrel. This is part of the USAMU’s Handloading Hump Day series, publiches on the USAMU Facebook page.
Beginning Handloading, Part 13:
Extrapolating Beyond Your Data, or … “I Don’t Know, What I Don’t Know!”
We continue our Handloading Safety theme, focusing on not inadvertently exceeding the boundaries of known, safe data. Bullet manufacturers’ loading manuals often display three, four, or more similar-weight bullets grouped together with one set of load recipes. The manufacturer has tested these bullets and developed safe data for that group. However, seeing data in this format can tempt loaders — especially new ones — to think that ALL bullets of a given weight and caliber can interchangeably use the same load data. Actually, not so much.
The researchers ensure their data is safe with the bullet yielding the highest pressure. Thus, all others in that group should produce equal or less pressure, and they are safe using this data.
However, bullet designs include many variables such as different bearing surface lengths, hardness, and even slight variations in diameter. These can occasionally range up to 0.001″ by design. Thus, choosing untested bullets of the same weight and caliber, and using them with data not developed for them can yield excess pressures.
This is only one of the countless reasons not to begin at or very near the highest pressure loads during load development. Always begin at the starting load and look for pressure signs as one increases powder charges.
Bullet bearing surface length (BSL) is often overlooked when considering maximum safe powder charges and pressures. In photo 1 (at top), note the differences in the bullets’ appearance. All three are 7mm, and their maximum weight difference is just five grains. Yet, the traditional round nose, flat base design on the left appears to have much more BSL than the sleeker match bullets. All things being equal, based on appearance, the RN/FB bullet seems likely to reach maximum pressure with significantly less powder than the other two designs.
Bearing Surface Measurement Considerations
Some might be tempted to use a bullet ogive comparator (or two) to measure bullets’ true BSL for comparison’s sake. Unfortunately, comparators don’t typically measure maximum bullet diameter and this approach can be deceiving.
Photo 2: The Perils of Measuring Bearing Surface Length with Comparators
In Photo 2, two 7mm comparators have been installed on a dial caliper in an attempt to measure BSL. Using this approach, the BSLs differed sharply from the original [measurements]. The comparator-measured Bullet 1 BSL was 0.694” vs. 0.324” (original), Bullet 2 was 0.601” (comparator) vs. 0.430” (original), and Bullet 3 (shown in Photo 2) was 0.602” (comparator) vs. 0.463” (original). [Editor’s comment — Note the very large difference for Bullet 1, masking the fact that the true full diameter on this bullet starts very far back.]
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Here’s a significant new addition to our knowledge base for Long-Range shooting. Hornady has released a new Ballistics Calculator that employs bullet profiles derived from Doppler radar testing and 3D projectile modeling. Hornady’s Patent Pending 4DOF™ Ballistic Calculator provides trajectory solutions based on projectile Drag Coefficient (not static G1/G7 ballistic coefficients) along with the exact physical modeling of projectiles and their mass and aerodynamic properties. This new 4DOF (Four Degrees of Freedom) calculator also accounts for spin drift and the subtle VERTICAL effects of crosswinds.
We strongly recommend you watch this video from start to finish. In greater detail than is possible here, this video explains how the 4DOF System works, and why it is more sophisticated than other commercially-offered Ballistics calculators. There’s a LOT going on here…
Aerodynamic Jump from Crosswind Calculated
According to Hornady, the 4DOF Ballistics Calculator “is the first publicly-available program that will correctly calculate the vertical shift a bullet experiences as it encounters a crosswind.” This effect is called aerodynamic jump. The use of radar-derived drag profiles, correct projectile dynamics, aerodynamic jump, and spin drift enable the Hornady® 4DOF™ ballistic calculator to provide very sophisticated solutions. Hornady says its 4DOF solver is “the most accurate commercially available trajectory program … even at extreme ranges.”
“Current ballistic calculators provide three degrees of freedom in their approach — windage, elevation, and range — but treat the projectile as an inanimate lump flying through the air,” said Dave Emary, Hornady Chief Ballistician. “This program incorporates the projectile’s movement in the standard three degrees but also adds its movement about its center of gravity and subsequent angle relative to its line of flight, which is the fourth degree of freedom.”
Using Doppler radar, Hornady engineers have calculated exact drag versus velocity curves for each bullet in the 4DOF™ calculator library. This means the 4DOF™ calculator should provicde more precise long range solutions than calulators that rely on simple BC numbers or drag curves based with limited data collection points. Emary adds: “The Hornady 4DOF also accurately calculates angled shots by accounting for important conditions that [other ballistic] programs overlook.”
“This calculator doesn’t utilize BCs (Ballistic Coefficients) like other calculators,” added Jayden Quinlan, Hornady Ballistics Engineer. “Why compare the flight of your bullet to a standard G1 or G7 projectile when you can use your own projectile as the standard?” That makes sense, but users must remember that Hornady’s 4DOF projectile “library” includes mostly Hornady-made bullets. However, in addition to Hornady bullets, the 4DOF Calculator currently does list seven Berger projectiles, six Sierra projectiles, and one Lapua bullet type. For example, Sierra’s new 183gr 7mm MatchKing is listed, as is Berger’s 105gr 6mm Hybrid.
This Video Explains How to Use Hornady’s New 4DOF Ballistics Calculator
Using the 4DOF™ Ballistic Calculator:
The Hornady 4DOF Ballistic Calculator provides trajectory solutions based on projectile Drag Coefficient (not ballistic coefficients) along with exact physical modeling of the projectile and its mass and aerodynamic properties. Additionally, it calculates the vertical shift a bullet experiences as it encounters a crosswind, i.e. “aerodynamic jump”. The use of drag coefficients, projectile dynamics, aerodynamic jump, and spin drift enable the 4DOF Ballistic Calculator to accurately measure trajectories even at extreme ranges. It is ideal for both long range and moderate distances and is available for the low-drag precision bullets listed in the drop down menu of the calculator. For calculating trajectories of traditional hunting and varmint bullets using BCs (ballistic coefficients), you can use Hornady’s Standard Ballistics Calculator.
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Here’s a tip we feature every year or so, because it is something that costs nothing, yet can be very useful in the reloading process. With a simple, easy modification to a fired case, you can determine the length to lands in your rifle barrel. As long as you set the tension right, the measurements should be repeatable, and you’ve just saved yourself $31 — the price of a commercial OAL gauge.
To achieve best accuracy with a rifle, you must control bullet seating depth very precisely, so all bullets end up in the same place relative to the entrance of the lands, every time. There may be multiple cartridge OALs which prove accurate. However, with each, you first need to determine a “zero” point — a reliable, and repeatable OAL where the bullet is “just touching” the lands.
There are tools, such as the Hornady (formerly Stoney Point) OAL Gauge, that will help you find a seating OAL just touching the lands. However, the tool requires that you use a special modified case for each cartridge you shoot. And, while we find that the Hornady OAL Gauge is repeatable, it does take some practice to get in right.
Make Your Own Length-to-Lands Gauge with a Dremel
Here’s an inexpensive alternative to the Hornady OAL tool — a slotted case. Forum member Andris Silins explais how to create a slotted case to measure length to the lands in your rifle:
“Here’s what I did to find length to lands for seating my bullets. I made four cuts into the neck of fire-formed brass. Then I pressed the bullet in lightly and chambered the entire gauge. As the cartridge chambers, the bullet slides back into the case to give you length to lands. It took less than five minutes to get it cut and working. A little light oil in the barrel just past the chamber helps ensure the bullet does not get stuck in the lands. It works great and is very accurate.
I made the cuts using a Dremel with a cut-off wheel. You can adjust tension two ways. First, you can make the cuts longer or shorter. Longer cuts = less tension. If you used only three cuts insted of four you would get more tension. The trick is to be gentle when you open and close the bolt. If you ram the bolt closed you may wedge the bullet into the lands. When you open the bolt it helps to keep a finger or two near by to guide the case out straight because the ejector wants to push it sideways.”
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At the request of our readers, we provide select “Deals of the Week”. Every Monday morning we offer our Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
1. Amazon — Caldwell Long Range Target Camera System, $349.49
Forum members have purchased this Caldwell Target Cam System and they’ve found that it works reliably, providing a clear signal to any WiFi-enabled mobile device (smartphone, iPad, Laptop). One member specifically tested the unit at 1000 yards and it functioned fine. NOTE: This system does NOT have a zoom camera lens, so you need to position the camera within 10 yards or so of the target. But if you place it to the side a bit, this shouldn’t be a problem. This system comes with a nice, fitted carrying case that holds camera, transceivers, antennas, and stands. You get a very capable system for under $350.00 (Amazon price includes free shipping for Prime members). You can also get this system from Midsouth for $357.02 (shipping extra).
2. Amazon — Tipton Gun Vise, $33.13 (free Prime Shipping)
This is an awesome deal on a durable, well-designed polymer Gun Vise that every rifle owner can use. Your Editor has one of these units which has served well for more than a decade. The base has compartments for solvents, patches, and tools. The cradles and pads contacting your gunstock are a soft, rubber-like material that is gentle on fine finishes. This vise is relatively light in weight, but sturdy enough to support big, heavy rifles. NOTE: This is currently back-ordered, but due in stock August 17, 2016.
3. Midsouth — Burris Eliminator LaserScope with $100.00 Rebate
The Burris Eliminator III is an impressive piece of electro-optical technology. The built-in laser rangefinder senses the distance to your target and the scope’s “brain” calculates the required hold-over. The calculated aiming point is then displayed with an illuminated red dot on the vertical cross-hair. Just put the bright red dot on the target and make the shot. We’ve used this scope out to 600 yards on small steel targets and it worked flawlessly. Right now you can get a $100 Factory REBATE plus attractive sale pricing from Midsouth. After rebate, the 3-12x44mm Eliminator III costs $1199.00.
Here’s a rifle with a smooth three-lug action and good trigger that can take any game in North America. The Browning A-Bolt is justifiably respected as a solid hunting rifle. The 300 Winchester Magnum chambering offers serious hitting power, even at long range. This rifle, with a blued barreled action, normally retails for $600.00+. Now it’s on sale for under $500.00. To sweeten the deal even more, right now Browning is offering $50 CASH BACK on Browning centerfire rifles purchased between August 1, 2016, and September 30, 2016. CLICK HERE for $50.00 REBATE FORM.
5. Grafs.com — Hornady Z-Max Poly-Tip Bullets, $64/500 and Up
It seems like the Zombie craze has run its course (thank goodness), so Hornady’s Zombie bullets are being sold off at very low prices. Graf & Sons acquired a truckload of the green-tipped Z-Max bullets. These are the same as the popular red-tip V-Max bullets, just with a different color for the tips. Choose .204, .224, or .308 calibers in a variety of bullet weights. Prices start at $63.99 for 500, 32 grain .204 caliber varmint bullets. That’s just $12.79 per hundred.
6. Grafs.com — Forster Co-Ax Reloading Press on SALE
The Forster Co-Ax is a unique press that loads very straight ammo. If you’ve been patiently waiting to acquire a Forster Co-Ax® reloading press, now’s the time to strike. Grafs.com has Co-Ax presses on sale at $289.99. That includes shipping charges (with one flat $7.95 handling charge per order).
7. Glen’s Army Navy — CCI 17 HMR Ammo, $10.99 for 50 Rounds
Here’s a good deal on 17 HMR ammo, our favorite cartridge type for small varmints. This quality CCI ammo is loaded with 20 grain jacketed SP bullets. Muzzle velocity is 2375 FPS. If you need 17 HMR ammo, you might want to act quickly. At this price this 17 HMR ammo will sell out.
8. Amazon — Two Rolls of 3″ Neon Target Stickers, $14.95
We like these bright Neon 3″ target stickers. They are big enough to see easily at 600 yards, giving you a 1/2 MOA target center at that distance. For $14.95 at Amazon.com, you get 250 3″-diameter self-adhesive centers (125 targets per roll) that stick to almost any surface The high-contrast fluorescent red/orange color provides an excellent HI-VIZ aiming point, along with good contrast for bullet holes that fall within the 3″ circle. To help line up your reticle cross-hairs, the target centers feature black markers at 3, 6, 9, and 12 O’clock.
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David Tubb has come out with a new, improved version of his heavyweight 6mm match bullet. David’s new DTAC 115gr 6mm projectile is very slippery — the tested G1 1000-yard BC is 0.620. The DTAC 115 features a Rebated Boat Tail (RBT) design and a factory-pointed tip (what David calls a “closed nose”). This bullet is in production now, priced at $145.00 for 500 bullets. David tell us “the new DTAC 115 has arrived” and his company is currently filling backorders. New orders will be taken at DavidTubb.com starting Monday, August 15th. You can also call 806-323-9488 (8:30 am-4:30 pm CT) to order.
David explained the two main reasons why the Rebated Boat Tail (RBT) design was chosen for the new DTAC 115 bullet:
1. It is easier to precisely hold tolerances when manufacturing the 7 degree boat tail angle. Most conventional boat tails have 9 degree angles (or greater).
2. The RBT more efficiently obturates to the bore of the rifle barrel when fired. (It mimics a flat base bullet design). This will allow the RBT design to extend your accurate barrel life by reducing gas leakage around the bullet when fired in a worn 6mm throat.
NOTE: David does NOT claim the RBT offers a higher BC compared to a conventional boattail design.
DESIGN FEATURES: DTAC 115 Bullet with Rebated Boat Tail
Commentary by David Tubb
In the 1980s we shot 107 grain weight-range 6mm bullets for Silhouette and High Power competitions. Lower recoil and good wind drift were paramount in coming to the 6mm bullet diameter.
After I developed the 6XC case around 2003 I approached Sierra about making me a 6mm bullet in the 115 grain range. Sierra ran prototypes in 112, 115, and 120 grain configurations. I thoroughly tested these and decided on the 115 grain. In 2004 I used these at Camp Perry and the result was a Long Range National Championship Aggregate with a perfect 1450×101 score. Enough said….
In 2007 Sierra had just introduced its plastic-tipped bullets. I had them run a test batch of plastic-tipped 117 grain weights. These didn’t pass my criteria.
We then ran another test batch of 111 grain plastic tip 6mm bullets and they looked great in the Sierra tunnel tests. However when shot them over an Oehler 43 at 1000 yards the results indicated the plastic tips were deformed or nonexistent at the target. These didn’t pass my criteria.
FYI — that plastic tip deformation testing information preceded the Hornady “Plastic tips Are Bad” advertising campaign by more than seven years.
When using a .308 early in my High Power rifle career we shot 190 grain Sierras at the 600-yard stage. When 600-yard accuracy began to fall off a switch to a 185gr Lapua rebated boat tail brought the accuracy back. I remember shooting some very high X-Count scores with 185gr Lapuas. The reason the Lapua worked in a worn barrel is because the rebated boat tail allows the bullet to obturate to fit the worn throat and prevent less gas leakage around the bullet when fired.
I had a bullet-maker friend reform some 6mm 115s with a rebated boat tail (RBT) in 2015 and had excellent results. So it was a natural move to redesign the current DTAC 115 6mm with a RBT and a 7 degree boat tail.
Ballistic Coefficent and Stabilization
High BC Confirmed
David says, “The new DTAC 115 RBT testing is complete and [we] can claim a G1 1000-yard BC of 0.620″.
Required Twist Rate for Stability
David reports: “This bullet stabilized out of true 1:8″ twist or faster barrel at velocities approaching 3000 fps at sea level”.
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Think you can “get by” without protective eyewear? This story provides yet another example of why you should wear safety glasses every time you go shooting. You only have one set of eyes — they are much too precious to risk.”
Bad Primer Blasts Gas Through Side of Casehead
Our friend Grant Guess recently had a “close encounter” with a bad primer. An apparently defective primer caused part of the casehead on one of his rounds to blow out. This, in turn, allowed high pressure gas to vent through the damaged primer pocket. Take a good look, boys and girls. This is yet another very good reason to wear safety glasses. The cartridge was a 6.5-06, hand-loaded in necked-down Winchester-headstamp .270 Win brass. Grant reports:
“I had a blow-through between the primer and the primer pocket today. The action was really smoking and I got a face full of gas. This was a reasonably light charge. Thank God for safety glasses.
I should also mention that it appears there is a 3/64 hole that is halfway between the primer and the primer pocket. Like it burned a small jet hole through both of them.”
Could this happen to you? It just might. On seeing this damaged case, one of Grant’s Facebook friends, Chris D., observed: “Search the internet, you will see a lot of these pin hole ‘in the corner’ failures. Obviously Winchester has some issues with the LR primers.”
Careful Examination Reveals Apparent Primer Defect
After this incident, Grant examined the damaged case: “I pinned the flash hole and it is not over-sized or under-sized. The primer clearly has an area where it had a defect. At [50,000 CUP], it doesn’t take much of a defect to cause issues. There was a slight bit of pucker-factor on the next shot….”
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At the request of our readers, we provide select “Deals of the Week”. Every Monday morning we offer our Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
1. Precision Reloading — 10% and 15% Off Berger Bullets
Berger projectiles have won countless matches and set scores of World Records. Now you can save big bucks on match and hunting bullets from Berger Bullets in a wide variety of calibers and weights. Right now Precision Reloading is offering 10% off orders of $100 or more (Code BG8161), and 15% off orders of $500.00 or more (Code BG8165). Precision Reloading has many of the most popular Berger match projectiles in stock, including 6mm 105gr Hybrids, and 7mm 180gr Hybrids. NOTE: This special only runs for a few more days, so don’t delay!
2. Midsouth — Lyman BoreCam Digital Borescope, $222.46
Here’s a great deal on an excellent product in high demand. The Lyman BoreCam is an electro-optical borescope with a digital display. You can record “stills” on a SD card. This is one of the hottest products on the market right now. But we found some in stock at a great price. Midsouth Shooters Supply now has the BoreCam for $222.46. Grab it while you can at that price. Other online vendors are charging a LOT more. For example, the MidwayUSA price is $259.99.
3. RCBS — Buy Green, Get Green Rebate
RCBS is running a very attractive Rebate Program currently. If you spend $300.00 on qualifying products you get a $75.00 rebate. Spend $50 and get a $10.00 Rebate. This program is limited to one (1) rebate redemption per calendar year, with a maximum of $75.00. CLICK HERE for more information. NOTE: To qualify, you must supply completed RCBS rebate coupon, original UPC barcodes from package, and original cash register receipt and/or dated, itemized sales invoice.
Get RCBS Chargemaster for $225.00 After Rebate
Using this rebate, you can get an RCBS Chargemaster from Amazon.com for a “final price” of $225.00. Amazon sells the Chargemaster for exactly $300.00 which qualifies for the $75.00 rebate.
4. Natchez Shooters Supply — 325 Rounds .22 LR Ammo, $22.99
This Federal .22 LR ammo is just 7 cents per round — the kind of pricing on bulk rimfire ammo we used to see in the “good old days”. Act quickly, this $22.99 Federal .22 LR Ammo deal won’t last long. Each box contains 325 rounds — enough ammo for many sessions at the range. The bullets are 40 grains, solid lead.
5. Grafs.com — Magnetospeed Sporter $179.99
If you have been waiting to get a Magnetospeed… wait no longer. Priced at just $179.99 at Grafs.com, the Magnetospeed Sporter model costs less than half as much as Magnetospeed’s V3 models. This chronograph attaches directly to your barrel so you don’t have to go downrange to position tripods and set up skyscreens. For most people the Sporter Model contains all the features they need. Using Magnetospeed’s XFR adapter (sold separately), data can be transferred easily from the display module to your mobile device. READ Magnetospeed Sporter Review.
This is a very good spotting scope for the price. Yes it gives up some low-light performance to a spotter with an 80mm objective, but otherwise it is a good performer, and we can’t think of much that will touch this Vortex Diamondback spotting scope for anywhere near the $399.99 sale price. Choose from angled or straight version for the same $399.99 price, which includes the 20-60X zoom eyepiece.
7. Amazon — Howard Leight Electronic Earmuffs $40.97
Every shooter should own a pair of Electronic muffs, even if you prefer shooting with earplugs and/or standard muffs. Electronic muffs are great when you are doing spotting duties or are working near the firing line. They allow you to hear ordinary conversations while still providing vital hearing protection. Right now Amazon.com has the Howard Leight Impact Sport Electronic Muffs on sale for just $40.97. This is good deal — these NRR 22 muffs are currently Amazon’s #1 seller in the category. NOTE: For regular, sustained shooting we recommend muffs and/or earplugs with a higher NRR rating.
8. Amazon — Leight MAX NRR33 Earplugs, $7.58 for 50 Pairs.
These Howard Leight NRR33 Max plugs are your Editor’s favorite foam earplugs. Between shooting, motorcycling and mowing lawns, I probably have Max plugs in my ears 2-3 days a week. This is a very good price for a bulk pack of 50 pairs. And if you act soon, you can get free shipping to boot.
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We first ran this story a few years back. But it’s still a very interesting subject for benchrest shooters. Shown above, the 30 BR (a 6mmBR necked up to .30 Caliber) currently rules the benchrest-for-score game. However, a 30 BR Improved offers some potential advantages, particularly when the winds are strong or tricky. In this article Al Nyhus explains his 30 BRX wildcat. Running Hodgdon H4198, Al says he gets an easy 150 -200 FPS more than the conventional 30 BR. That can translate to less drift in the wind. It also lets you pursue a higher speed node, which can lead to improved accuracy with some barrels.
Forum member Al Nyhus is a top-level score shooter who has competed successfully with the 30 BR cartridge in VFS (Varmint for Score) matches. Al has been working on an “improved” 30 BR cartridge that delivers extra velocity. Al’s 30 BRX cartridge is inspired by the 6mm BRX cartridge, popular in 600-yard benchrest and across-the-course competition. The 6mm BRX cartridge maintains the same sidewall profile and shoulder angle as the parent 6mmBR case. Likewise, the 30 BRX retains the 30° shoulder used on the popular 30 BR cartridge.
Al reports: “Thought you might like to see what I’ll be working with in my VFS gun this season. It’s a true 30 BRX — a 30 BR with the shoulder moved forward 0.100″ with the standard BR shoulder angle. Stan Ware of SGR Custom Rifles built one last season for Steve Grosvenor and I was really impressed by the performance of Steve’s gun. The 30 BR barrel on my VFS gun needed replacing, so the new 30 BRX got the nod.”
30 BRX Delivers 150-200 FPS More Velocity than 30 BR
Al says his 30 BRX gives a solid 150-200 fps speed gain over the 30 BR at the top, while needing just 2.5-3.0 more grains of Hodgdon H4198 to do so. A 30 BR case holds on average 40.8 grains of water, while the 30 BRX holds 42.3 grains (roughly 4% more). So the 30 BRX delivers a 7% increase in velocity with a mere 4% increase in H20 capacity. That’s pretty good efficiency. [Editor’s Note: Assuming 34 grains of H4198 is a typical 30 BR match load, Al’s increase of 2.5-3.0 grains for the 30 BRX represents roughly a 7.5-8.5% increase in actual powder burned. That explains the higher velocities.]
Why did Nyhus decide to try an “improved” 30 BR?
Al explains: “The 30 BRX was created to operate at a [higher] velocity level than can be achieved with the standard 30 BR case, while at the same time keeping the easy-tuning characteristics of the standard 30 BR case. We also wanted to use the same powders currently used with the 30 BR and maintain similar operating pressures.” Is the 30BRX harder to shoot because of the increased velocity? Al doesn’t think so: “In a 13.5-lb HV gun, the 30 BRX case is a pleasure to shoot with just a flea bite of recoil.”
Will the 30 BRX Replace the 30 BR in Score Competition?
The 30 BR is already an exceptionally accurate cartridge that dominates short-range Benchrest for Score competition. Will the 30 BRX make the standard 30 BR obsolete? Nyhus doesn’t think so. However, Al believes the 30 BRX offers a small but important edge in some situations: “On any given day, it’s the shooter that hits the flags best and makes the fewest mistakes that ends up on top. No amount of velocity will save you when you press the trigger at the wrong time. Missing a switch or angle change at 200 yards that results in 3/4″ of bullet displacement on the target can’t be compensated for with another 200 fps. That’s the hard fact of benchrest shooting. But on those days when, as Randy Robinett says, ‘our brains are working’, the BRX may offer enough of an advantage to turn a close-but-no-cigar 10 into an ‘X’ at 200 yards. Or turn a just-over-the-line 9 into a beggar 10.” Given the fierce competition in Score matches, an extra 10 or another X can make the difference between a podium finish and also-ran status.
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Wouldn’t it be nice to have a print resource at your fingertips that has hundreds of true-size cartridge illustrations, plus technical descriptions of thousands of popular cartridge types? That could be a real time-saver. It’s no wonder this book is an Amazon best-seller in its category.
If you’re a serious shooter, the latest 5th Edition of the Ammo Encyclopedia belongs in your library. This 1008-page book by Michael Bussard is probably the most comprehensive and up-to-date book in print covering current and obsolete cartridges and shotshells. The Ammo Encyclopedia is a massive resource work. The 5th Edition now boasts 105 chapters, covering thousands of handgun, rifle, and shotgun cartridges from the past century and a half.
One of the best features is a 12-page color section depicting actual size drawings of 265 current rimfire/centerfire cartridges and shotshells. You won’t find that many “life-size” cartridge drawings in one place even on the internet. Cartridge profiles and ballistic charts have been expanded to include all new factory cartridges. The authors have even included air rifle pellets and historical images and charts. Softcover, 1008 pages — edited by S.P. Fjestad.
Comments from guys who bought the book:
“This book contains a vast array of information on many modern and even obsolete ammunition. Definitely recommend for any modern reloader novice or experienced.” – Duggaboy460
“It’s a great reference book for individuals who reload their own ammunition. There is a lot more info in this Edition. Everyone who likes this information should have it in their library.” – Reloader
“I like the general and technical comments that are available for each and every cartridge. Information that predicts if a cartridge will stay in production for many more years or rapidly become obsolete.” – RSL1
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In this video, Bryan Litz of Applied Ballistics talks about Density Altitude and the effect of atmospheric conditions on bullet flight. Bryan explains why you must accurately account for Density Altitude when figuring long-range trajectories.
Bryan tells us: “One of the important elements in calculating a fire solution for long-range shooting is understanding the effect of atmospherics. Temperature, pressure, and humidity all affect the air density that the bullet’s flying through. You can combine all those effects into one number (value) called ‘Density Altitude’. That means that you just have one number to track instead of three. But, ultimately, what you are doing is that you are describing to your ballistics solver the characteristics of the atmosphere that your bullet’s flying through so that the software can make the necessary adjustments and account for it in its calculations for drop and wind drift.”
Bryan adds: “Once you get past 500 or 600 yards you really need to start paying careful attention to atmospherics and account for them in your ballistic solutions”. You can learn more about Density Altitude in Bryan’s book, Applied Ballistics for Long Range Shooting (Third Edition).
General Scientific Definition of Density Altitude
Density altitude is the altitude relative to the standard atmosphere conditions (ISA) at which the air density would be equal to the indicated air density at the place of observation. Density altitude can be calculated from atmospheric pressure and temperature (assuming dry air). Here is the formula:
Air is more dense at lower elevations primarily because of gravity: “As gravity pulls the air towards the ground, [lower] molecules are subject to the additional weight of all the molecules above. This additional weight means the air pressure is highest at sea level, and diminishes with increases in elevation”.*
Both an increase in temperature, decrease in atmospheric pressure, and, to a much lesser degree, increase in humidity will cause an increase in density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.
Based on the questions we get on a daily basis on our 800 (Customer Support) line, twist is one of the most misunderstood subjects in the gun field. So let’s look deeper into this mystery and get a better understanding of what twist really means.
When you see the term 1:14″ (1-14) or 1:9″ twist, just exactly what does this mean? A rifle having a 1:14″ twist means the bullet will rotate one complete revolution every fourteen inches of the barrel. Naturally a 1:9″ turns one time every nine inches that it travels down the barrel. Now, here’s something that some people have trouble with. I’ve had calls from shooters thinking that a 1:14″ twist was faster than a 1:9″ because the number was higher with the 1:14″. The easiest way to remember this is the higher the number, the slower the twist rate is.
Now, the biggest misconception is that if a shooter has a .223 with a 1:8″ twist, his rifle won’t stabilize a 55gr bullet or anything lighter. So let’s look at what is required. The longer a bullet is for its diameter, the faster the twist has to be to stabilize it. In the case of the .223 with a 1:8″ twist, this was designed to stabilize 80gr bullets in this diameter. In truth the opposite is true. A 1:8″ will spin a 55gr faster than what is required in order to stabilize that length of bullet. If you have a bullet with good concentricity in its jacket, over-spinning it will not [normally] hurt its accuracy potential. [Editor’s Note: In addition, the faster twist rate will not, normally, decrease velocity significantly. That’s been confirmed by testing done by Bryan Litz’s Applied Ballistics Labs. There may be some minor speed loss.]
Many barrel-makers mark the twist rate and bore dimensions on their barrel blanks.
Think of it like tires on your truck. If you have a new set of tires put on your truck, and they balance them proper at the tire shop, you can drive down a street in town at 35 MPH and they spin perfect. You can get out on the highway and drive 65 MPH and they still spin perfect. A bullet acts the same way.
Once I loaded some 35gr HP bullets in a 22-250 Ackley with a 1:8″ twist. After putting three shots down range, the average velocity was 4584 FPS with an RPM level of 412,560. The group measured .750″ at 100 yards. This is a clear example that it is hard to over-stabilize a good bullet.
Twist-rate illustration by Erik Dahlberg courtesy FireArmsID.com. Krieger barrel photo courtesy GS Arizona.
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22Plinkster Tours CCI/Speer Idaho Factory
Trickshot artist and YouTube host 22Plinkster recently got a chance to tour the CCI/Speer production facility in Lewiston, Idaho. This large plant produces both rimfire and centerfire ammunition. While touring the plant, 22Plinkster was allowed to capture video showing the creation of .22 LR rounds from start to finish. This is a fascinating video, well worth watching.
This revealing video shows all phases of .22 LR ammo production including cupping, drawing, annealing, washing, drying, head-stamping, priming, powder charging, bullet seating, crimping, waxing, inspection, and final packaging. If you’ve got ten minutes to spare, we really recommend you watch the video from start to finish. You’ll definitely learn some new things about rimfire ammo.
.22 Plinkster was literally up to his neck in ammo while touring the CCI/Speer Idaho ammo plant. He says: “This was truly a dream come true for me. I can’t thank the people at CCI and Speer enough for allowing me to do this. I couldn’t possibly show everything that went on at the factory. However, hopefully I showed you enough for you to grasp the concept of how rimfire [ammo] is made.”
Speer Brothers Brought Ammo Production to Lewiston
Here is an interesting historical footnote. Today’s large CCI/Speer operation in Idaho can be traced back to the companies founded by the Speer brothers. After settling in Lewiston in 1944, Vernon Speer started Speer Bullets. A few years later, in 1951, Vernon’s brother Dick (with partner Arvid Nelson) started Cascade Cartridges Inc., a producer of small-arms ammunition and primers. Yes, as you may suspect, Cascade Cartridges Inc. is now CCI, a Vista Outdoor company, and one of the largest manufacturers of primers and loaded ammunition. Today, the CCI/Speer Lewiston plant produces both Speer bullets and CCI-branded ammunition and primers. Vista Outdoor’s predecessor, ATK, acquired the plant in 2001. Vernon Speer died in 1979, and Dick Speer died in 1994.
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Chuck’s Pair of Pennsylvania Dashers
There’s been a lot of interest in the 6mm Dasher cartridge lately, so we thought we’d showcase a matched pair of Dasher rifles belonging to a Forum member. The 6mm Dasher began as a wildcat improved version of the 6mmBR Norma cartridge. The 6mm Dasher has been very successful in competition, and now factory Norma-made Dasher cartridge brass is available from Bullets.com.
Forum Member Chuck L. (aka “Ridgeway”) has created a handsome duo of 6mm Dashers for competitive benchrest and varmint matches in Pennsylvania. Both guns are built on Kelbly Panda RBLP actions, with Bartlein 8-twist barrels, and Shehane Laminated Tracker Stocks. However, the two rifles are not exact twins, as you can see. One, which we’ll call the Big Dasher, is built on a Shehane ST1000 Tracker stock. The other gun, the Small Dasher, sports Shehane’s “Baby Tracker” stock — a design used with great success by Richard Schatz. The Big Dasher, optimized for 1000-yard competition, also has a slightly longer freebore — 0.136″ vs. 0.104″ for the Small Dasher.
Specifications for the Dasher Duo:
Small Dasher (13.5-pounder): Chambered for 6mm Dasher with approximately .104 freebore and a .264 NK. (No way of knowing exactly since it freebore was done in a separate operation by Kelbly.) Components are: Shehane Baby Tracker stock, Kelbly Panda RPLB action, Bartlein 1:8″ LV barrel at 26 ¾”, Kelbly Rings, Weaver T36, Jewell trigger. The barrel was chambered by Kelblys and the stock was bedded, glued and balanced by a shooting buddy (Forum Member johara1). I clear-coated the stock with auto urethane. Total weight is 13 lbs., 4 ounces.
Big Dasher (1K Light Gun, 17-pounder): Chambered for 6mm Dasher with a .136 freebore and .264 neck (PTG Reamer). Components are: Shehane ST-1000 stock, Kelbly Panda RPLB action, Bartlein 1:8″ HV 5R barrel at 28″, Shehane +20-MOA rings, Nightforce NXS 12-42x56mm, Jewell trigger. The barrel work, pillar installation, and bedding was done by Dave Bruno. The stock was clear-coated by Chuck with auto urethane. Chuck also made the rear butt plate and balanced the rifle. Total weight: 16 lbs., 13 ounces.
Chuck tells us: “I don’t get out shooting competition as much as I want due to time and family, but when I do compete, I shoot a Groundhog match at Southfork Rifle Club in Beaverdale, PA. Info on Southfork Club events can be found at Southforkrifleclub.com. The Southfork match is basically a 100-, 300- and 500-yard match with one sighter the entire match and 5 shots at each yardage for score. The Small Dasher, with the shorter ‘Baby Tracker’ stock, was set up for the Southfork Rifle Club’s ‘Light Unlimited’ class which has a 13.5-lb max weight.” (Editor: ‘unlimited’ is a misnomer for a weight-limited category.)
Chuck adds: “The Big Dasher with the heavy ST-1000 stock is set up for 1000-yard benchrest matches in Light Gun class. I hope to shoot a couple 1K matches with it at Reade Range in southwest Pennsylvania. I am still in load development for this rifle since it was just finished in January. One ironic thing is, it shoots the same load I’m shooting out of the lighter gun rather well. The only difference between the two chambers is the freebore is roughly thirty thousandths longer on the 1K gun (Large Dasher). I will also shoot this at Southfork in the ‘Heavy Unlimited’ class.”
Dasher Case-Forming: Neck-Turn then Fire-form with Bullets Hard in Lands
To fireform, I turn my cases down to fit the chamber and stop where the false shoulder makes snug contact with the chamber. Fire-forming rounds are loaded up with a 29-grain charge of H4895 or Varget and a 108gr Berger bullet seated hard into the lands about 0.020″ past initial contact with the rifling. It takes about three firings to make a nice clean Dasher case with a sharp shoulder. I anneal about every 3-4 firings. I have many cases that have about 10+ firings on them and they are still shooting well. The primer pockets are a little looser, but still hold a primer.
Both Dashers Group in the Ones at 100 Yards
My main bullet for both rifles is the 107gr Sierra MK, loaded with Reloder 15 powder, Lapua cases and CCI 450 primers. My main load for the Small Dasher is 33.0 grains of Reloder 15. This load shoots in the ones at 100 yards. For the Big Dasher, I’m still working on a load, although the same 33.0 grain load shoots in the ones in the heavier gun as well. I’m still looking for more velocity and my ‘max’ node. So far, I’ve gone well above 33.0 grains of RL 15 without pressure signs, but that load produces vertical at 100 yards, so I’m going to tinker with the load until I see pressure or it starts to shoot.
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In this video, Bryan Litz of Applied Ballistics explains how to choose a bullet for long-range shooting and explains what you should be looking for when developing a long-range load. Bryan notes that, with a new rifle build, the bullet you select may actually dictate your gun components. When starting from a “clean slate”, once you select a bullet, you will then pick a barrel, twist rate, and cartridge that are appropriate for that bullet. In choosing a long-range projectile, Bryan recommends you choose a high-BC bullet “that is known for precision”. Then you need to find an ultra-consistent, reliable load.
This video is worth watching. Bryan Litz makes some very good points.
Load Development — Why Consistency is Key (and Half-MOA May Be Good Enough)
After choosing a bullet for your long-range project, then you need to develop a load through testing. Bryan explains: “Once you’ve selected a bullet … and you have selected the components around that bullet, the most important thing to remember in hand-loading is consistency. You’re going to do some testing to see what combination of powder charge, powder type, and seating depth give you the best groups and lowest standard deviations in muzzle velocity.”
Bryan says that if you develop a load that can shoot consistent, half-minute groups in all conditions, you should be satisfied. Bryan says that many long-range shooters “spin their wheels” trying to achieve a quarter-MOA load. Often they give up and start all over with a new bullet, new powder, and even a new cartridge type. That wastes time, money, and energy.
Bryan cautions: “My advice for hand-loaders who are long-range shooters, is this: If you can get a load that is reliable and can shoot consistent, half-minute groups with low MV variation and you can shoot that load in any condition and it will work well, then STICK with THAT LOAD. Then focus on practicing, focus on the fundamentals of marksmanship. The consistency you develop over time by using the same ammunition will mean more to your success in long range shooting than refining a half-minute load down to a quarter-minute load.”
Bryan notes that, at very long range, shooting skills and wind-calling abilities count most: “Your ability to hit a 10″ target at 1000 yards doesn’t improve very much if you can make your rifle group a quarter-minute vs. a half a minute. What’s going to determine your hit percentage on a target like that is how well you can calculate an accurate firing solution and center your group on that target. A lot of people would be more effective if they focused on the fire solution and accurately centering the group on the target [rather than attempting to achieve smaller groups through continuous load development].”
Editor’s Note: We agree 100% with the points Bryan makes in this video. However, for certain disciplines, such as 600-yard benchrest, you WILL need a sub-half-MOA rifle to be competitive at major matches. Well-tuned, modern 600-yard benchrest rigs can shoot 1/4-MOA or better at 100 yards. Thankfully, with the powder, bullets, and barrels available now, 1/4-MOA precision (in good, stable conditions) is achievable with a 17-lb benchgun built by a good smith with premium components.
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Figure 1. When the bullet is seated farther out of the case, there is more volume available for powder. This enables the cartridge to generate higher muzzle velocity with the same pressure.
Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1 by Bryan Litz forBerger Bullets.
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. Cartridge Overall Length (COAL) is also a variable that can be used to fine-tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a magazine. In this article, we’ll explore the various effects of COAL, and what choices a shooter can make to maximize the effectiveness of their hand loads.
Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI)
Most loading manuals (including the Berger Manual), present loading data according to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) standards. SAAMI provides max pressure, COAL and many other specifications for commercial cartridges so that rifle makers, ammo makers, and hand loaders can standardize their products so they all work together. As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.
Bullet seating depth is an important variable in the accuracy equation. In many cases, the SAAMI-specified COAL is shorter than what a hand loader wants to load their rounds to for accuracy purposes. In the case where a hand loader seats the bullets longer than SAAMI specified COAL, there are some internal ballistic effects that take place which are important to understand.
Effects of Seating Depth / COAL on Pressure and Velocity
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long. In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short.
When you think about it, it makes good sense. After all, when you seat the bullet out longer and leave more internal case volume for powder, you’re effectively making the cartridge into a bigger cartridge by increasing the size of the combustion chamber. Figure 1 illustrates the extra volume that’s available for powder when the bullet is seated out long.
Before concluding that it’s a good idea to start seating your bullets longer than SAAMI spec length, there are a few things to consider.
Geometry of a Chamber Throat
The chamber in a rifle will have a certain throat length which will dictate how long a bullet can be loaded. The throat is the forward portion of the chamber that has no rifling. The portion of the bullet’s bearing surface that projects out of the case occupies the throat (see Figure 2).
The length of the throat determines how much of the bullet can stick out of the case. When a cartridge is chambered and the bullet encounters the beginning of the rifling, known as the lands, it’s met with hard resistance. This COAL marks the maximum length that a bullet can be seated. When a bullet is seated out to contact the lands, its initial forward motion during ignition is immediately resisted by an engraving force.
Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.
A very common practice in precision reloading is to establish the COAL for a bullet that’s seated to touch the lands. This is a reference length that the hand loader works from when searching for the optimal seating depth for precision. Many times, the best seating depth is with the bullet touching or very near the lands. However, in some rifles, the best seating depth might be 0.100″ or more off the lands. This is simply a variable the hand loader uses to tune the precision of a rifle.
What happens inside a rifle chamber and barrel when a cartridge fires can’t be seen by the naked eye (unless you are a Super-Hero with X-Ray vision). But now, with the help of 3D-style computer animation, you can see every stage in the process of a rifle round being fired.
In this amazing video, X-Ray-style 3D animation illustrates the primer igniting, the propellant burning, and the bullet moving through the barrel. The video then shows how the bullet spins as it flies along its trajectory. Finally, this animation shows the bullet impacting ballistic gelatin. Watch the bullet mushroom and deform as it creates a “wound channel” in the gelatin. This excellent video was commissioned by Czech ammo-maker Sellier & Bellot to demonstrate its hunting ammunition. The design, 3D rendering, and animation was done by Grafické studio VLADO.
Watch Video – Cartridge Ignition Sequence Starts at 1:45 Time-Mark
Video find by Seb Lambang. We welcome reader submissions.
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Berger Twist-Rate Stability Calculator
On the Berger Bullets website you’ll find a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This cool tool tells you if your chosen bullet will really stabilize in your barrel.
How to Use Berger’s Twist Rate Calculator
Using the Twist Rate Calculator is simple. Just enter the bullet DIAMETER (e.g. .264), bullet WEIGHT (in grains), and bullet overall LENGTH (in inches). On its website, Berger conveniently provides this info for all its bullet types. For other brands, we suggest you weigh three examples of your chosen bullet, and also measure the length on three samples. Then use the average weight and length of the three. To calculate bullet stability, simply enter your bullet data (along with observed Muzzle Velocity, outside Temperature, and Altitude) and click “Calculate SG”. Try different twist rate numbers (and recalculate) until you get an SG value of 1.4 (or higher).
Gyroscopic Stability (SG) and Twist Rate
Berger’s Twist Rate Calculator provides a predicted stability value called “SG” (for “Gyroscopic Stability”). This indicates the Gyroscopic Stability applied to the bullet by spin. This number is derived from the basic equation: SG = (rigidity of the spinning mass)/(overturning aerodynamic torque).
If you have an SG under 1.0, your bullet is predicted not to stabilize. If you have between 1.0 and 1.1 SG, your bullet may or may not stabilize. If you have an SG greater than 1.1, your bullet should stabilize under optimal conditions, but stabilization might not be adequate when temperature, altitude, or other variables are less-than-optimal. That’s why Berger normally recommends at least 1.5 SG to get out of the “Marginal Stability” zone.
In his book Applied Ballistics For Long-Range Shooting, Bryan Litz (Berger Ballistician) recommends at least a 1.4 SG rating when selecting a barrel twist for a particular bullet. This gives you a safety margin for shooting under various conditions, such as higher or lower altitudes or temperatures.
Story idea from EdLongrange. We welcome reader submissions.
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